Photoelectrochemical (PEC) technologies provide a direct route for converting solar energy into fuels and value-added chemicals. While remarkable progress has been achieved in the development of photoelectrode materials, the transition from laboratory demonstrations to practical applications remains limited by challenges in scalable manufacturing, reactor engineering, long-term stability, and operation under realistic conditions. Advancing PEC technologies toward higher technology readiness levels therefore requires moving beyond the optimization of individual photoelectrodes toward the development of integrated systems designed for manufacturability, process intensification, and real-world deployment.

A first challenge is the scalable fabrication of photoelectrodes. Simply increasing electrode dimensions is insufficient because limitations associated with conductive substrates and charge transport rapidly compromise device performance. Industrially compatible manufacturing methods are therefore essential for producing reproducible photoelectrodes over large areas while minimizing material consumption and waste. Among the available approaches, screen printing represents a promising route for the fabrication of metal-oxide semiconductor photoanodes owing to its scalability, versatility, compatibility with large-area substrates, and potential for industrial implementation.

As PEC devices increase in size, reactor engineering becomes equally important for controlling light distribution, mass transport, electrical losses, electrode configuration, and product separation. Modular reactor architectures based on segmented photoelectrodes offer an attractive strategy for overcoming the limitations associated with monolithic large-area electrodes while enabling flexible electrical configurations and progressive scale-up. Such designs also facilitate coupling with solar concentrators and outdoor operation, providing a realistic pathway toward intensified solar chemical production.

Beyond materials and reactor design, improving the technical and economic viability of PEC technologies also requires reaction engineering and operation under realistic conditions. Current strategies include replacing the oxygen evolution reaction with more valuable oxidation processes, coupling photoanodes with selective reduction reactions to maximize overall process value, integrating photoelectrochemical and bioelectrochemical systems to exploit their complementary operating windows, and operating under concentrated sunlight to increase solar-to-chemical productivity. Together, these approaches broaden the application space of PEC technologies while improving their overall efficiency and sustainability.

Overall, this contribution presents systems-level strategies for advancing photoelectrochemical technologies beyond laboratory-scale demonstrations. By integrating scalable photoelectrode manufacturing, modular reactor engineering, alternative reaction pathways, hybrid photo(bio)electrochemical systems, and operation under realistic solar conditions, the work illustrates how materials science, device engineering, and process design can be combined to accelerate the transition of PEC technologies toward practical solar-driven chemical production. The examples presented are drawn from complementary developments carried out within the DISTECH2, PHOENIX, and ALGAESOL projects, highlighting a common strategy for advancing PEC systems from fundamental materials to integrated technologies with higher technology readiness levels.